5 papers · 1 filter
Complete Non-Selfadjointness of Extensions of Symmetric Operators with Bounded Dissipative Perturbations
Christoph Fischbacher, Andrés Felipe Patiño López, Monika Winklmeier
Using boundary triples, we develop an abstract framework to investigate the complete non-selfadjointness of the maximally dissipative extensions of dissipative operators of the for…
Maximally dissipative and self-adjoint extensions of -invariant operators
Christoph Fischbacher, Bart Rosenzweig, Jonathan Stanfill
We introduce the notion of -invariant operators, , (in a Hilbert space) with respect to a bounded and boundedly invertible operator defined via . Conditions such…
An analysis of non-selfadjoint first-order differential operators with non-local point interactions
Christoph Fischbacher, Danie Paraiso, Chloe Povey-Rowe +1
We study the spectra of non-selfadjoint first-order operators on the interval with non-local point interactions, formally given by . We giv…
Nonnegative extensions of Sturm-Liouville operators with an application to problems with symmetric coefficient functions
Christoph Fischbacher, Jonathan Stanfill
The purpose of this paper is to study nonnegative self-adjoint extensions associated with singular Sturm-Liouville expressions with strictly positive minimal operators. We provide…
Abstract Left-Definite Theory: A Model Operator Approach, Examples, Fractional Sobolev Spaces, and Interpolation Theory
Christoph Fischbacher, Fritz Gesztesy, Paul Hagelstein +1
We use a model operator approach and the spectral theorem for self-adjoint operators in a Hilbert space to derive the basic results of abstract left-definite theory in a straightfo…